Three-dimensional shape measurement based on speckle-embedded fringe patterns and wrapped phase-to-height lookup table

Abstract

A three-dimensional (3D) shape measurement method based on speckle-embedded fringe patterns (composite fringe patterns) and wrapped phase-to-height lookup table (LUT) is proposed. As an auxiliary signal, speckle is embedded into the phase domain of the projected fringes, and the wrapped phase and deformed speckle modulated by the objects are demodulated by phase-shifting algorithm. With the assistance of the LUT established in advance, the candidate heights are directly obtained by the wrapped phase. Subsequently, the speckle correlation is used to eliminate the height ambiguity, and then the absolute spatial height of the measured objects can be reconstructed without projecting any additional pattern. In this paper, the cooperation of embedded speckle and LUT allows the speckle to do correlation operation in some certain smaller area of the candidate heights’ location, instead of matching within the whole measurement range, thus it can improve the computational efficiency in the determination of the unique accurate height. Theoretical analysis and experimental results have demonstrated that the proposed method can achieve high-accuracy and robust 3D shape measurement of dynamic and static complex scenes.